1. Field of the Invention
The present invention relates to a computer program product for managing logical connections between devices connected to an IEEE 1394 serial bus (hereinafter referred to simply as “bus”).
2. Description of the Related Art
Today, there is increasing use of networks in which audio and video devices are connected to each other via an IEEE 1394 serial bus cable (hereinafter referred to simply as “cable”). In this kind of network, connected devices in the network are unable to send and receive stream data such as e.g. video signals and audio signals between them when they are only physically connected to the network via the cable. More particularly, in order for the connected devices to send and receive stream data between them, it is necessary to establish a logical connection between a connected device to send stream data and a connected device to receive the stream data in accordance with the IEC 61883-1 standard. Commercially available controllers are designed to, for example, establish a logical connection between a target device and the controller automatically by background processing when the controller causes the target device to start playing and to release the logical connection automatically by background processing when the controller causes the target device to stop playing, so that the logical connection is transparent to a user.
However, the above described method of establishing and releasing a logical connection between connected devices on a bus automatically by background processing has the disadvantage of prohibiting a user from checking whether or not the logical connection has been successfully established between the connected devices. This may cause the user to be anxious about whether or not stream data can be appropriately sent and received between the relevant connected devices.
It is relatively easy for a conventional controller to establish a logical connection between the controller itself and its target device. For example, assuming that the controller is a hard disk recorder, a logical connection with a target device is established in the following manner. When a user selects a Dubbing button 101 shown in FIG. 23, the controller displays a window 102 for showing a list of target devices to which a target file can be copied. Subsequently, when the user selects a target device (a button 103 representing the target device) to which the file is to be copied from among the target devices displayed in the window 102, the controller automatically establishes the logical connection between the selected target device and the controller itself. However, one problem associated with the conventional controller is that it cannot establish a logical connection between a freely-selected combination of target devices.
Japanese Laid open Patent Publication 2003-216516 discloses a device designed to, upon selection of an output device from an output device list, display whether or not the selected output device can be logically connected with each of input devices in an input device list, and to logically connect the selected output device with an input device selected from among input devices that are indicated as being logically connectable with the output device. Such a device may be able to establish a logical connection between a freely-selected combination of target devices, but it also has the above described disadvantage of prohibiting a user from checking whether or not a logical connection has been successfully established between connected devices. Further, the device is not designed to display listing data concerning the devices connected to the bus in such a format that can show physical and logical connections existing between the connected devices. Accordingly, it is not easy for a user to know which connected devices have to remain physically connected to each other in order to maintain a currently active logical connection.